Inertia switch



Patented May 5, 1953 UNITED STATES PATENT OFFICE INERTIA SWITCH StanleyBleier, Asbury Park, N. J., assignor to the United States of America asrepresented by the Secretary of the Army Application July 7, 1950,Serial No. 172,581

(Granted under Title 35, U. S. Code (1952),

see. 266) 6 Claims.

ter consists of a small, self-contained, cylindri cally-shaped unitincluding a microwave receiver, a microwave transmitter, and anelectronic detonator exciter. Such a beacon is used as a tracking aidinmissiles or similar devices. In operation, the electronic detonatorexciter is energized only by a received signal having a specificcharacteristic, and it responds to such signal to effect the firing ofan externally-connected electric detonator.

With the beacon installed in a rocket or other missile, there is thedanger of premature detonation of the firing circuit, with consequentdamage to the missile and possible serious injury to personnel.

With the foregoing in mind, it is oneof the objects of my invention toprovide an improved inertia switch adapted particularly for use intransponder beacons and which, by virtue of its structural and operatingcharacteristics prevents the firing circuit of the detonator excitedunit from functioning until the rocket or missile is far enough away inits flight from the launching site. Accidental discharge, therefore,would not be too dangerous.

Other objects and advantages will hereinafter appear.

For the purpose of illustrating my invention, an embodiment thereof isshown in the drawing, wherein Figure 1 is a front, elevational view ofan inertia switch embodying and operating in accordance with myinvention;

Fig. 2 is an elevation'al view, looking toward the left in Fig. 1;

Fig. 3 is a section taken on the line 3-3 in Fig. 2; and

Fig. 4 is a view similar to Fig. 8, and illustrativ of the operatingaction.

In my improved inertia switch, a compressed spring II) is effective tohold a piston II yieldingly in the extreme lefthand position in acylinder I2, as shown in Fig. 3. A switch unit I4 is disposed betweentwo plates I5 and IS with which the cylinder structure is provided, andis fixed to the latter by studs I! which pass through plate I5 and arescrewedinto the insulating base I8 of the switch unit.

A fixed contact I9 and a movable, spring-contact 20 are disposed in thebase I8 in the relative positions shown, and are held in place by theterminal studs 2I and 22, respectively. Extending through spring-contact20 and insulated therefrom by a bushing 23, is a pin 24 which is held orlocked in 'a raised position, as shown in Fig. 3, when engaged with theouter cylindrical surface of piston II In this position, pin 24 holds orlooks spring-contact 20 out of engagement with contact I9.

When installed, for example, in a transponder beacon, the cylinder I2 01.my improved inertia switch is fixed with respect to the beacon casing,and the arrangement or orientation is such that the direction of travelfrom the launching site is toward the left as viewed in Figs. 3 and 4,and in line with piston I I and cylinder I2. Due to the accelerationofcylinder I2 when the rocket and the beacon contained therein arelaunched, and because of the inertia of piston I I, the latter will lagbehind cylinder I2 and the tension of spring ID will increase'inproportion to occurring movement of the cylinder relatively with respectto the piston. In a specific design, the action was such that piston I Iwould assume the relative position shown in Fig.4 only at an impact ofabout 5 Gs acceleration, and then only if such acceleration weremaintained for approximately ten seconds. There were two factors whichentered into this characteristic action. One of these was the adjustmentof screw-25 to vary the initial tension of loading spring Ill. The otherfactor was the damping or dash-pot action provided by the continuouspassage 26, Z'Ifroni one end of piston II to the other end thereof. Bychoosing the right, respective diameters for the passages 25 and 21, thepermissible rate of air-flow through piston II is obtained to'give thecorrect amount of damping or dash-pot action for the operatingcharacteri tics desired.

\Vhen the impact is suflicient as the rocket is launched, and when therate' of acceleration persists for the predetermined number of seconds,piston II will reach the position shown in Fig. 4, relatively withrespect to cylinder I2. Pin 24 will then be free to slip off the end ofcylinder I2 under the spring-action of contact 2n, and the latter willengage contact I9, as shown, to effect completion of the firing circuitof the detonator exciter unit referred to.

To reset my improved inertia switch, an upward pull is exerted on theknob 28 fixed on the end of pin 24, until the latter clears piston IIwhich is then free to snap back to its initial position shown in Fig. 3,under the loading force exerted by spring Ill.

In the; specific design referred to, the length of piston M was, oneinch, and! the. diameter of the bore 01' passage '26 was approximately.016 inch. The respective dimensions of the other parts were inproportion, as shown in th drawing, all the figures of which are drawnto thesame scale.

Examples of other specific; uses to; which my improved inertia switchmight be put are shown. in Patent No. 915,246, issued March 16,1909,,to- Harry F. Stratton, in Patent No. 21883144; is-

sued January 23, 1940, to Frank A, Eytman, and;

in Patent No. 2,431,027, issued November-1.8, 1.947., to John W.Busacker et a1.

One of the broader aspects of my invention resides in the provision ofan inertia switch wherein some suitable means, such as the compressedspring I 0, operates to hold two. members such as cylinder ['2 and;piston, H yieldingly in: an.- initial relative. position as shown. in:Fig. 3, and wherein there is incorporated some, form of switch meanssuchas the: unit M1 arran ed to beopened when the two members are intheinitial relative position and to be closed when these members: are in asecond relative position; as shown. in Fig 4.

While but one embod ment: of my invention has been and describeditiwill'be understood! by those skilled" in. the art; that: variousmodifications, such as in the size, shape and arrancement of the parts.might be made without departin from the spirit of nay-invention, or thescope of the claims.

The invention claimed is:-

1. In an inertia switch of the character described, a. cylinder; apiston disposed in said cylinder and mo able relatively with respectthereto. from an initiai position at; one end of said cylinder to: asecond position. toward the other end or said cylinder, a. coil springcompressed between said piston and said. other end of; said cylinden.and: a switch unit disposed at one side of said? cylinder: saidunitcomprisinc a base of insulating material fixed to; said cylinden aswitch contact fixed in said? base, and a sprin contact. supported bysaid base and; movableinto and out of engagement" with said: fixedcontact, saidv spring-contact beinggpnovided with a. pin one: end ofwhich extends loosely through said: base-and? through the adjacent:cylinder; wall for engagement with the: cylindrical surface of saidpiston to hold said spring-contact. disengaged: fronr said fixedcontact, the; disposition: of said; pin longitudinally of said. cylinderbein such that: with. saidpist'onin said second: "position thereof saidpin; is released. by' said piston to permit engagement. of; saidspring-contact with said fixed contact, said piston, being: providedwith a passage OfrelatiVeIy small" cross-sectional area and extendingfrom: one. end? to the: other end; of said piston. to; effect: adash'spot action against a relatively rapid movement of? said. pistonfrom said; initial; position to said second position, thereof, the:-other end off said pin. protruding from said" base to. permitwithdrawal! of. said pinout of said cylinder.

2. In an. inertia. switch of the: character described, acylindenprovided' on onesidethereof with two plates spaced? and parallelwith respect to each other; a piston disposed in said cylinder andmovable relatively with respect thereto from an initial position at oneend of said cylinderto a second position toward the other end of saidcylinder,-a coil spring compressed between said piston and said otherend of said cylinder, and a switch unit disposed between and fixed tosaid plates; said, unit. comprising a base, of insulating material, a;switch contactfixcd in saidbase, and a U-shape spring-contact disposedwithin said base and fixed to the latter at one end, the other end ofsaid spring-contact being disposed for movement into and out ofengagement with said fixed. contact, saidspring-contact being providedat said. other end thereof with a pin one end of which; extends .looselythrough said base and through the adjacent cylinder Wall for engagementwith the cylindrical surface of said piston to-hold said other end ofsaid spring-contact disengaged from said fixed contact, the dispositionof said pin longitudinally of said cylinder being such that with saidpiston in said second position thereof said pin is: released by saidpiston to permit engagement of said other end of said springrcontactwithsaid, fixed contact...

3,. In,v an inertiaswitch of the character described, a cylinder, apiston disposed in said cylinderand movable relatively with respectthereto from an initia1 position at one end of said cylinder to avsecond position toward the other end of said cylinder, a. springcompressed. between said piston and. said. other end of said cylinder,and a switch unit disposed atone side i of said cylinder; said unitcomprising a base. of

insulating material fixed to said cylinder, a switch. contact fixed in.said base, and a. springcontact. supported bysaid base and. movable intoand out: of engagement with said fixed contact, said. spring-contactbeing providedwithapin one end of which extends loosely through saidbase and through the adjacent cylinder wall for engagementwith the;cylindrical surface of saidpiston to hold said spring-contact disengagedfrom said fixed contact, the, disposition of said pin longitudinally of.said cylinder being. such. that with said piston, in. said second.position thereof saidv pin" is released by said piston to permitengagement of said spring-contact with said fixed contact and, saidpistonbeing provided with a passage extending fromone. end to. the otherend of said piston.

4., In an inertia switch of the character described, a cylinder, apiston disposed in said cylinder and movable relatively with respectthereto from an initial position at. one end of said cylinder to; a.second position toward the other end of said cylinder, a springcompressed between said piston and said other end of said cylinder, andswitch means spring-biased to one position and having at least one partthereof engageable with said piston and disposed to be locked in anotherposition. by virtue of such ongagement, said piston being provided witha passage extending from one end to the other end of said piston toregulate the movement of said piston.

5'. In an inertia: switch. of. the. character described, a cylinder, apiston disposed in said cylinder, a spring compressed between saidpiston and one end of said cylinder, and switch means spring-biased toonevpositi'on and having at least one part thereof engageable with thecylindrical surface of said" piston, and disposed to. be locked inanother position by virtue of said engagement, said piston being movableaxially along said cylinder to a given position toward said one end ofthe latter to disengage said part from said cylindrical surface therebyto effect movement of said switch means to another posi- ReferencesCited in the file of this patent UNITED STATES PATENTS Name DateBoothroyd Mar. 15, 1938 Number Number Number Name Date Gilbert July 28,1942 Gilbert Oct. 6, 1942 Haiderson Oct. 17, 1944 FOREIGN PATENTSCountry Date Germany July 2, 1932 France Dec. 28, 1925

